Mixed
Training frequency does not significantly impact muscle hypertrophy (measured by circumference) when total training volume is equated.
If your goal is muscle size, focus on hitting your total weekly sets and reps, not how many days you train. Whether you train 3 or 4 days a week, as long as the total volume is the same, your muscle growth will be similar. Do not feel pressured to add extra days just for the sake of frequency.
Schoenfeld et al. [23] in a systematic review and meta-analysis of 25 studies reported that 'there is strong evidence that resistance training frequency does not significantly or meaningfully impact muscle hypertrophy when volume is equated,' which is in line with our finding that gains in muscle size are not in relation to training frequency...
Why this rating
Consistent with meta-analyses cited; the study itself found no significant group x time interaction for circumference, supporting the null hypothesis for frequency effects on size.
Source
Effects of a resistance training program on muscular performance adaptations: comparing three vs. four times per week
Hossein Firoozi et al. · Biomedical Human Kinetics · 2020
DOI 10.2478/bhk-2020-0019
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